The subject matter herein relates generally to electrical relay devices.
Electrical relay devices are generally electrically operated switches used to control the presence or absence of current flowing through a circuit from a power source to one or more other electrical components. The power source may be one or more batteries, for example. Some electrical relays use an electromagnet to mechanically operate a switch. The electromagnet may physically move a movable electrical contact relative to one or more stationary contacts. The movable electrical contact may form or close a circuit (allowing current to flow through the circuit) when the movable contact engages one or more of the stationary contacts. Moving the movable electrical contact away from the stationary contact(s) breaks or opens the circuit.
At least some electrical relay devices include a ferromagnetic element that is disposed at least proximate to the electromagnet such that an induced magnetic field applies a magnetic force upon the ferromagnetic element that translates the ferromagnetic element relative to the electromagnet. The ferromagnetic element is coupled to a shaft, which extends from the ferromagnetic element to the movable electrical contact. The shaft is coupled to both the ferromagnetic element and the movable electrical contact. Therefore, movement of the ferromagnetic element due to the induced electrical field causes movement of the shaft and the movable electrical contact towards and away from the stationary contacts, forming or braking a circuit, as described above.
Known electrical relay devices have some disadvantages. For example, the coupling between the shaft and the ferromagnetic element in some known electrical relay devices is made via a separate fastener. An additional fastener is used to couple the shaft to the moving electrical contact. The particular fasteners used in some known relay devices are retaining rings, such as E-clips or C-clips. But, since the retaining rings are separate fasteners that are installed to engage to discrete parts, the retaining rings are prone to moving out of position, and even falling off of the parts completely. The electrical relay devices may be used on vehicles, such as trains and automobiles. Vibrations and other forces encountered during use and/or improper installment during assembly may cause the retaining rings to loosen, dislodge, and finally fall off. At such time, the shaft may uncouple from the ferromagnetic element and/or the movable electrical contact. In either event, the movable electrical contact would no longer be coupled, indirectly via the shaft, to the ferromagnetic element, such that translation of the ferromagnetic element would not control movement of the movable electrical contact and the electrical relay device would cease to function until the fasteners or new fasteners are replaced.
A need remains for an electrical relay device that does not use separate fasteners to couple the shaft to the movable electrical contact and to the ferromagnetic element.